This project, originally begun when Dr. Bailey-Wilson was a Professor at Louisiana State University Medical Center, has been temporarily discontinued due to inadequate personnel time. The purpose of this project is to perform a search for evidence of a major locus affecting risk of colorectal cancer using family history data collected by questionnaire from colorectal cancer patients who did not have either Familial Polyposis Coli or Hereditary Non-Polyposis Colorectal Cancer. The specific aim of this project is to perform segregation analysis on a set of data provided by Dr. Henry Lynch of Creighton University. Analyses using REGTL and REGTLhunt of the S.A.G.E. computer package indicate evidence that such a major susceptiblity locus may exist.